As used herein the term “carbonaceous feedstock” is a material that has “fixed carbon feedstock components” and “volatile feedstock components”.
As used herein the term “fixed carbon feedstock components” refers to feedstock components present in a carbonaceous feedstock other than volatile feedstock components, contaminants, ash or moisture. Fixed carbon feedstock components are usually solid combustible residue remaining after the removal of moisture and volatile feedstock components from a carbonaceous feedstock.
As used herein the term “volatile feedstock components” refers to components within a carbonaceous feedstock other than fixed carbon feedstock components, contaminants, ash or moisture.
As used herein the term “product gas” refers to volatile reaction products, syngas, or flue gas discharged from a thermochemical reactor undergoing thermochemical processes including hydrous devolatilization, steam reforming, partial oxidation, dry reforming, or combustion.
As used herein the term “syngas” refers to a gaseous mixture containing carbon monoxide (CO), hydrogen (H2), and other vapors/gases, also including char, if any and usually produced when a carbonaceous material reacts with steam (H2O), carbon dioxide (CO2) and/or oxygen (O2). While steam is the reactant in steam reforming, CO2 forms the reactant in dry reforming. Generally, for operation at a specified temperature, the kinetics of steam reforming is faster than that of dry reforming and so steam reforming tends to be favored and more prevalent.
As used herein the term “volatile reaction products” refers to vapor or gaseous non-polar organic species that were once present in a solid or liquid state as volatile feedstock components of a carbonaceous feedstock wherein their conversion or vaporization to the vapor or gaseous state was promoted by the process of hydrous devolatilization. Volatile reaction products may contain both, non-condensable species, and condensable species which are desirable for collection and refinement.
As used herein the term “flue gas” refers to a vapor or gaseous mixture containing varying amounts of nitrogen (N2), carbon dioxide (CO2), water (H2O), and oxygen (O2). Flue gas is generated from the thermochemical process of combustion.
As used herein the term a “thermochemical process” refers to a broad classification including various processes that can convert a carbonaceous feedstock into product gas. Among the numerous thermochemical processes or systems that can be considered for the conversion of a carbonaceous material, the present disclosure contemplates: hydrous devolatilization, steam reforming, partial oxidation, dry reforming, and combustion. Thermochemical processes may be either endothermic or exothermic in nature depending upon the specific set of processing conditions employed. Stoichiometry and composition of fluidization medium, type of fluidization medium, fluid bed temperature and pressure, heating rate of the feedstock, residence time, feedstock properties, and catalyst or bed additives all dictate what sub classification of thermochemical processing the system exhibits.
As used herein the term “thermochemical reactor” refers to a fluidization reactor that accepts a carbonaceous feedstock and converts it into one or more product gases.
As used herein the term “hydrous devolatilization” refers to an endothermic thermochemical process wherein volatile feedstock components of a carbonaceous feedstock are converted primarily into volatile reaction products in a steam and hydrogen environment; however some syngas can be generated. Typically this sub classification of a thermochemical process involves the use of steam as a fluidization medium and involves temperatures ranging from 320° C. and 569.99° C., depending upon the feedstock chemistry. Hydrous devolatilization permits release and thermochemical reaction of volatile feedstock components leaving the fixed carbon feedstock components mostly unreacted as dictated by kinetics.
As used herein the term “steam reforming” refers to a thermochemical process comprising a specific chemical reaction where steam reacts with a carbonaceous feedstock to yield syngas. The main reaction is endothermic wherein the operating temperature range is between 570 and 900° C., depending upon the feedstock chemistry.
As used herein the term “dry reforming” refers to a thermochemical process comprising a specific chemical reaction where carbon dioxide is used to convert a carbonaceous feedstock into syngas. By limiting the amount of water available, the main reaction is endothermic wherein the operating temperature range is between 600 and 1,000° C., depending upon the feedstock chemistry.
As used herein the term “partial oxidation” refers to a thermochemical process wherein substoichiometric oxidation of a carbonaceous feedstock takes place to generate syngas. By limiting the amount of oxygen available, the main reaction is exothermic wherein the operating temperature range is between 500 and 1400° C., depending upon the feedstock chemistry.
As used herein the term “combustion” refers to a thermochemical process wherein at least the stoichiometric oxidation of a carbonaceous feedstock takes place to generate flue gas.